Targeting miR-10a-5p/IL-6R axis for reducing IL-6-induced cartilage cell ferroptosis

Metformin alleviates spinal cord injury by inhibiting nerve cell ferroptosis through upregulation of heme oxygenase-1 expression

JOURNAL/nrgr/04.03/01300535-202409000-00037/figure1/v/2024-01-16T170235Z/r/image-tiff Previous studies have reported upregulation of heme oxygenase-1 in different central nervous system injury models. Heme oxygenase-1 plays a critical anti-inflammatory role and is essential for regulating cellular redox homeostasis. Metformin is a classic drug used to treat type 2 diabetes that can inhibit ferroptosis. Previous studies have shown that, when used to treat cardiovascular and digestive system diseases, metformin can also upregulate heme oxygenase-1 expression. Therefore, we hypothesized that heme oxygenase-1 plays a significant role in mediating the beneficial effects of metformin on neuronal ferroptosis after spinal cord injury. To test this, we first performed a bioinformatics analysis based on the GEO database and found that heme oxygenase-1 was upregulated in the lesion of rats with spinal cord injury. Next, we confirmed this finding in a rat model of T9 spinal cord compression injury that exhibited spinal cord nerve cell ferroptosis. Continuous intraperitoneal injection of metformin for 14 days was found to both upregulate heme oxygenase-1 expression and reduce neuronal ferroptosis in rats with spinal cord injury. Subsequently, we used a lentivirus vector to knock down heme oxygenase-1 expression in the spinal cord, and found that this significantly reduced the effect of metformin on ferroptosis after spinal cord injury. Taken together, these findings suggest that metformin inhibits neuronal ferroptosis after spinal cord injury, and that this effect is partially dependent on upregulation of heme oxygenase-1.

Neopterin mediates sleep deprivation-induced microglial activation resulting in neuronal damage by affecting YY1/HDAC1/TOP1/IL-6 signaling

INTRODUCTION

Sleep deprivation (SD) is a common disorder in modern society. Hippocampus is an important region of the brain for learning, memory, and emotions. Dysfunction of hippocampus can lead to severe learning and memory disorder, significantly affecting quality of life. SD is accompanied by hippocampal microglia activation and a surge in inflammatory factors, but the precise mechanism remains unclear. Moreover, the ongoing unknown persists regarding how activated microglia in SD lead to neuronal damage. Topoisomerase 1 (TOP1) plays an essential role in the inflammatory process, including the tumor system and viral infection. In this study, we observed a significant elevation in TOP1 levels in the hippocampus of mice subjected to SD. Therefore, we hypothesize that TOP1 may be implicated in SD-induced microglia activation and neuronal damage.

OBJECTIVES

To investigate the role of TOP1 in SD-induced microglial activation, neuronal damage, and neurobehavioral impairments, and the molecular basis of SD-induced elevated TOP1 levels.

METHODS

TOP1-specific knockout mice in microglia were used to study the effects of TOP1 on microglial activation and neuronal damage. Transcription factor prediction, RNA interference, ChIP-qPCR, ChIP-seq database analysis, and luciferase reporter assays were performed to explore the molecular mechanisms of YY1 transcriptional activation. Untargeted metabolic profiling was employed to investigate the material basis of YY1 transcriptional activation.

RESULTS

Knockdown of TOP1 in hippocampal microglia ameliorates SD-induced microglial activation, inflammatory response, and neuronal damage. Mechanistically, TOP1 mediates the release of IL-6 from microglia, which consequently leads to neuronal dysfunction. Moreover, elevated TOP1 due to SD were associated with neopterin, which was attributed to its promotion of elevated levels of H3K27ac in the TOP1 promoter region by disrupting the binding of YY1 and HDAC1.

CONCLUSION

The present study reveals that TOP1-mediated microglial activation is critical for SD induced hippocampal neuronal damage and behavioral impairments.

Exacerbated ischemia-reperfusion injury in fatty livers is mediated by lipid peroxidation stress and ferroptosis

BACKGROUND

Ischemia-reperfusion injury is a common problem in liver surgery and transplantation. Although ischemia-reperfusion injury is known to be more pronounced in fatty livers, the underlying mechanisms for this difference remain poorly understood. We hypothesized that ferroptosis plays a significant role in fatty liver ischemia-reperfusion injury due to increased lipid peroxidation in the presence of stored iron in the fatty liver. To test this hypothesis, the ferroptosis pathway was evaluated in a murine fatty liver ischemia-reperfusion injury model.

METHODS

C57BL6 mice were fed with a normal diet or a high fat, high sucrose diet for 12 weeks. At 22 weeks of age, liver ischemia-reperfusion injury was induced through partial (70%) hepatic pedicle clamping for 60 minutes, followed by 24 hours of reperfusion before tissue harvest. Acyl-coenzyme A synthetase long-chain family member 4 and 4-hydroxynonenal were quantified in the liver tissues. In separate experiments, liproxstatin-1 or vehicle control was administered for 7 consecutive days before liver ischemia-reperfusion injury.

RESULTS

Exacerbated ischemia-reperfusion injury was observed in the livers of high fat, high sucrose diet fed mice. High fat, high sucrose diet + ischemia-reperfusion injury (HDF+IRI) livers had a significantly greater abundance of acyl-coenzyme A synthetase long-chain family member 4 and 4-hydroxynonenal compared with normal diet + ischemia-reperfusion injury (ND+IRI) livers or sham fatty livers, which indicated an increase of ferroptosis. HFD fed animals receiving liproxstatin-1 injections had a significant reduction in serum aspartate transaminase and alanine transaminase after ischemia-reperfusion injury, consistent with attenuation of ischemia-reperfusion injury in the liver.

CONCLUSION

Ferroptosis plays a significant role in ischemia-reperfusion injury in fatty livers. Inhibiting ferroptotic pathways in the liver may serve as a novel therapeutic strategy to protect the fatty liver in the setting of ischemia-reperfusion injury.

Bioinformatics Analysis and Identification of Ferroptosis-Related Hub Genes in Intervertebral Disc Degeneration

Approximately 80% of individuals encounter lower back pain (LBP), a prevalent clinical issue largely attributed to intervertebral disc degeneration (IDD). Ferroptosis is an iron-dependent lipid peroxidation-driven cell death, and there is growing evidence that ferroptosis plays an important role in various human diseases. However, the underlying mechanism of ferroptosis in IDD remains unclear. This study aims to reveal the potential hub genes and related pathways of ferroptosis in the pathogenesis and progression of IDD. In this study, we analyzed three microarray datasets from the GEO database. Additionally, we downloaded ferroptosis-related genes from FerrDb-V2 and extracted apoptosis-related genes from UniProt as a control to show the specificity of ferroptosis. Weighted gene co-expression network analysis (WGCNA) was performed to identify the IDD-related module genes. Then, ferroptosis-related genes and apoptosis-related genes were separately overlapped with the IDD-related module genes, resulting in the identification of 35 ferroptosis-related module genes (FRMG) and 142 apoptosis-related module genes (ARMG). Furthermore, we performed functional enrichment analysis and protein-protein interaction network, and Cytoscape along with CytoHubba was used to identify the hub genes. Finally, logistic regression models were constructed and identified two hub FRMGs (PTEN and EGFR) and one hub ARMG (CTNNB1), which could distinguish IDD patients from controls (P < 0.05). The areas under the ROC curves were 0.792 and 0.730, respectively, suggesting that ferroptosis is more specific than apoptosis in IDD. In conclusion, this study provided fresh perspectives on ferroptosis in the pathogenesis and progression of IDD that can be used to evaluate potential biomarker genes and therapeutic targets.

Spermidine protects cartilage from IL-1β-mediated ferroptosis

Rheumatoid arthritis is characterized by a burst of inflammation, the destruction of cartilage and the abundant release of inflammatory factors such as IL-1β. Thus, the effect of IL-1β on cartilage was examined in this study. IL-1β could cause lipid peroxidation and disturbances in iron metabolism by increasing the expression of NCOA4 and decreasing the expression of FTH, which also induced ferritinophagy. In addition, the expression of the key antioxidant proteins SLC7A11 and GPX4 was inhibited by IL-1β, resulting in ferroptosis in chondrocytes. Spermidine (SPD), a low-molecular-weight aliphatic nitrogen-containing compound that widely exists in animals, has been reported to be an antioxidant. In our study, we found that SPD could inhibit ferritinophagy and reverse the decrease in the expression of SLC7A11 and GPX4. Therefore, we uncovered one of the molecular mechanisms of cartilage destruction and inflammation and provide a potential polyamine for the treatment of RA.

New insights into the antimicrobial mechanism of LEAP2 mutant zebrafish under Aeromonas hydrophila infection using transcriptome analysis

Liver-expressed antimicrobial peptide 2 (LEAP2) is a blood-derived antimicrobial peptide expressed predominantly in the liver. Although LEAP2 has been reported to exert antimicrobial effects in various fish species, its antimicrobial mechanism is not entirely understood. Zebrafish is an intensively developing animal model for studying bacterial diseases. In this study, we used zebrafish to identify the role of LEAP2 in bacterial infection. We found that knockout of LEAP2 in zebrafish led to a higher bacterial burden and mortality. To further investigate the effect of LEAP2 mutation on the immune system, we conducted a comparative transcriptome analysis of zebrafish with a mutant of LEAP2. Based on gene ontologies (GO) enrichment, LEAP2 mutant zebrafish revealed that, compared to wild-type zebrafish, robust responses to bacteria, inflammatory factors, and disrupt immune homeostasis and induct hyperinflammation. Furthermore, based on Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, six immune pathways were identified: Phagosome, NOD-like receptor, ferroptosis, Cytokine-cytokine receptor, Toll-like receptor, and FOXO signalling pathways. Interestingly, besides the liver, muscle, intestine, and eggs are also significantly enriched to the ferroptosis pathway, as revealed using quantitative polymerase chain reaction (qPCR), further confirmed that the effect of LEAP2 mutations on inflammatory factors and ferroptosis-related genes. Most importantly, this is the first report of the zebrafish LEAP2 mutant transcriptome obtained using high-throughput sequencing. Our study employed comparative transcriptome analysis to reveal the inflammatory response and ferroptosis-signalling pathway as a novel potential mechanism of LEAP2 antibacterial activity, laying the foundation for future studies of LEAP2 immune functions.

Integrative bioinformatics analysis to screen key genes and signalling pathways related to ferroptosis in obesity

Ferroptosis is closely associated with the development of disease in the body. However, there are few studies on ferroptosis-related genes (FRGs) in obesity. Therefore, key genes and signalling pathways related to ferroptosis in obesity were screened. Briefly, the RNA sequencing data of obesity and the non-obesity human samples and 259 FRGs were downloaded from GEO database and FerrDb database, respectively. The obesity-related module genes were firstly screened by weighted gene co-expression network analysis (WGCNA) and crossed with differentially expressed genes (DEGs) of obesity/normal samples and FRGs to obtain obesity-ferroptosis related (OFR) DEGs. Then, key genes were screened by PPI network. Next, the correlation of key genes and differential immune cells between obesity and normal samples were further explored by immune infiltration analysis. Finally, microRNA (miRNA)-messenger RNA (mRNA), transcription factor (TF)-mRNA networks and drug-gene interaction networks were constructed. As a result, 17 OFR DEGs were obtained, which mainly participated in processes such as lipid metabolism or adipocyte differentiation. The 4 key genes, STAT3, IL-6, PTGS2, and VEGFA, constituted the network. M2 macrophages, T cells CD8, mast cells activated, and T cells CD4 memory resting had significant differences between obesity and normal samples. Moreover, 51 miRNAs and 164 drugs were predicted for 4 key genes. All in all, this study has screened 4 FRGs, including IL-6, VEGFA, STAT3, and PTGS2, in obesity patients.

Targeting Ferroptosis in Bone-Related Diseases: Facts and Perspectives

Ferroptosis is a new cell fate decision discovered in recent years. Unlike apoptosis, autophagy or pyroptosis, ferroptosis is characterized by iron-dependent lipid peroxidation and mitochondrial morphological changes. Ferroptosis is involved in a variety of physiological and pathological processes. Since its discovery, ferroptosis has been increasingly studied concerning bone-related diseases. In this review, we focus on the latest research progress and prospects, summarize the regulatory mechanisms of ferroptosis, and discuss the role of ferroptosis in the pathogenesis of bone-related diseases, such as osteoporosis (OP), osteoarthritis (OA), rheumatoid arthritis (RA), and osteosarcoma (OS), as well as its therapeutic potential.

Identification of a novel competing endogenous RNA network and candidate drugs associated with ferroptosis in aldosterone-producing adenomas

Aldosterone-producing adenoma (APA), characterized by unilaterally excessive aldosterone production, is a common cause of primary aldosteronism. Ferroptosis, a recently raised iron-dependent mode of programmed cell death, has been involved in the development and therapy of various diseases. This study obtained datasets of the mRNA and lncRNA expression profiles for APA and adjacent adrenal gland (AAG) from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and lncRNAs (DE lncRNAs) associated with ferroptosis were identified. Enrichment analyses indicated 89 ferroptosis-related DEGs were primarily enriched in ROS related processes and ferroptosis. Two physical cores, and one combined core were identified in the protein-protein interaction (PPI). DEGs and clinical traits were used in conjunction to screen eight hub genes from two hub modules and 89 DEGs. A competitive endogenous RNA (ceRNA) network was constructed via co-express analysis. Thereafter, molecular docking was used to identify potential targets. Two active compounds, QL-X-138 and MK-1775, bound to AURKA and DUOX1, respectively, with the lowest binding energies. Molecular dynamics simulation verified the stability of the two complexes. In summary, our studies identified eight hub genes and a novel ceRNA regulatory network associated with ferroptosis, wherein QL-X-138 and MK-1775 were considered to be potential drugs for treating APA.

Biological principles of adult degenerative scoliosis

The global aging population has led to an increase in geriatric diseases, including adult degenerative scoliosis (ADS). ADS is a spinal deformity affecting adults, particularly females. It is characterized by asymmetric intervertebral disc and facet joint degeneration, leading to spinal imbalance that can result in severe pain and neurological deficits, thus significantly reducing the quality of life. Despite improved management, molecular mechanisms driving ADS remain unclear. Current literature primarily comprises epidemiological and clinical studies. Here, we investigate the molecular mechanisms underlying ADS, with a focus on angiogenesis, inflammation, extracellular matrix remodeling, osteoporosis, sarcopenia, and biomechanical stress. We discuss current limitations and challenges in the field and highlight potential translational applications that may arise with a better understanding of these mechanisms.

Targeting regulated chondrocyte death in osteoarthritis therapy

In vivo articular cartilage degeneration is an essential hallmark of osteoarthritis (OA), involving chondrocyte senescence, extracellular matrix degradation, chondrocyte death, cartilage loss, and bone erosion. Among them, chondrocyte death is one of the major factors leading to cartilage degeneration. Many studies have reported that various cell death modes, including apoptosis, ferroptosis, and autophagy, play a key role in OA chondrocyte death. Currently, there is insufficient understanding of OA pathogenesis, and there remains a lack of treatment methods to prevent OA and inhibit its progression. Studies suggest that OA prevention and treatment are mainly directed to arrest premature or excessive chondrocyte death. In this review, we a) discuss the forms of death of chondrocytes and the associations between them, b) summarize the critical factors in chondrocyte death, c) discuss the vital role of chondrocyte death in OA, d) and, explore new approaches for targeting the regulation of chondrocyte death in OA treatment.

EGR1 knockdown confers protection against ferroptosis and ameliorates intervertebral disc cartilage degeneration by inactivating the MAP3K14/NF-κB axis

This study explored whether EGR1-MAP3K14-NF-κB axis regulated ferroptosis and IVD cartilage generation. EGR1 and MAP3K14 expression levels were determined in CEP tissues of IVDD patients and intermittent cyclic mechanical tension (ICMT)-treated CEP cells. After EGR1 and MAP3K14 were altered in ICMT-treated CEP cells, the expression levels of degeneration- and ferroptosis-related proteins were measured. Binding relationship between EGR1 and MAP3K14 was evaluated. Additionally, the impacts of EFR1 knockdown on ferroptosis and cartilage degeneration in vivo were analyzed. EGR1 and MAP3K14 were overexpressed in clinical samples and cell models of IVDD. In IVDD cell models, EGR1 knockdown reduced ferroptosis and cartilage degeneration, which was reversed by MAP3K14 overexpression or Erastin treatment. NF-κB pathway inhibition nullified these effects of sh-EGR1 + oe-MAP3K14 treatment. EGR1 knockdown inhibited ferroptosis and relieved CEP degeneration via MAP3K14-NF-κB axis inactivation in vivo. Collectively, our findings highlighted that EGR1 promoted ferroptosis and IVD cartilage degeneration through MAP3K14-NF-κB axis.

High-Tech Methods of Cytokine Imbalance Correction in Intervertebral Disc Degeneration

An important mechanism for the development of intervertebral disc degeneration (IDD) is an imbalance between anti-inflammatory and pro-inflammatory cytokines. Therapeutic and non-therapeutic approaches for cytokine imbalance correction in IDD either do not give the expected result, or give a short period of time. This explains the relevance of high-tech medical care, which is part of specialized care and includes the use of new resource-intensive methods of treatment with proven effectiveness. The aim of the review is to update knowledge about new high-tech methods based on cytokine imbalance correction in IDD. It demonstrates promise of new approaches to IDD management in patients resistant to previously used therapies, including: cell therapy (stem cell implantation, implantation of autologous cultured cells, and tissue engineering); genetic technologies (gene modifications, microRNA, and molecular inducers of IDD); technologies for influencing the inflammatory cascade in intervertebral discs mediated by abnormal activation of inflammasomes; senolytics; exosomal therapy; and other factors (hypoxia-induced factors; lysyl oxidase; corticostatin; etc.).

Functional micro-RNA drugs acting as a fate manipulator in the regulation of osteoblastic death

Bone loss is prevalent in clinical pathological phenomena such as osteoporosis, which is characterized by decreased osteoblast function and number, increased osteoclast activity, and imbalanced bone homeostasis. However, current treatment strategies for bone diseases are limited. Regulated cell death (RCD) is a programmed cell death pattern activated by the expression of specific genes in response to environmental changes. Various studies have shown that RCD is closely associated with bone diseases, and manipulating the death fate of osteoblasts could contribute to effective bone treatment. Recently, microRNA-targeting therapy drugs have emerged as a potential solution because of their precise targeting, powerful curative effect, and limited side effects. Nevertheless, their clinical application is limited by their inherent instability, easy enzymatic degradation, and poor membrane penetrability. To address this challenge, a self-assembling tetrahedral DNA nanostructure (TDN)-based microRNA (Tmi) delivery system has been proposed. TDN features excellent biocompatibility, cell membrane penetrability, serum stability, and modification versatility, making it an ideal nucleic acid carrier for miRNA protection and intracellular transport. Once inside cells, Tmi can dissociate and release miRNAs to manipulate key molecules in the RCD signaling pathway, thereby regulating bone homeostasis and curing diseases caused by abnormal RCD activation. In this paper, we discuss the impact of the miRNA network on the initiation and termination of four critical RCD programs in bone tissues: apoptosis, autophagy, pyroptosis, and ferroptosis. Furthermore, we present the Tmi delivery system as a miRNA drug vector. This provides insight into the clinical translation of miRNA nucleic acid drugs and the application of miRNA drugs in bone diseases.

The role of ferroptosis in intervertebral disc degeneration

Nucleus pulposus, annulus fibrosus, and cartilage endplate constitute an avascular intervertebral disc (IVD), which is crucial for spinal and intervertebral joint mobility. As one of the most widespread health issues worldwide, intervertebral disc degeneration (IVDD) is recognized as a key contributor to back and neck discomfort. A number of degenerative disorders have a strong correlation with ferroptosis, a recently identified novel regulated cell death (RCD) characterized by an iron-dependent mechanism and a buildup of lipid reactive oxygen species (ROS). There is growing interest in the part ferroptosis plays in IVDD pathophysiology. Inhibiting ferroptosis has been shown to control IVDD development. Several studies have demonstrated that in TBHP-induced oxidative stress models, changes in ferroptosis marker protein levels and increased lipid peroxidation lead to the degeneration of intervertebral disc cells, which subsequently aggravates IVDD. Similarly, IVDD is significantly relieved with the use of ferroptosis inhibitors. The purpose of this review was threefold: 1) to discuss the occurrence of ferroptosis in IVDD; 2) to understand the mechanism of ferroptosis and its role in IVDD pathophysiology; and 3) to investigate the feasibility and prospect of ferroptosis in IVDD treatment.

Micronutrients/miRs/ATP networking in mitochondria: Clinical intervention with ferroptosis, cuproptosis, and calcium burden

The mitochondrial electron transport chain (mtETC) requires mainly coenzyme Q10 (CoQ10), copper (Cu2+), calcium (Ca2+), and iron (Fe2+) ions for efficient ATP production. According to cross-sectional research, up to 50% of patients with micronutrient imbalances have been linked to oxidative stress, mitochondrial dysfunction, reduced ATP production, and the prognosis of various diseases. The condition of ferroptosis, which is caused by the downregulation of CoQ10 and the activation of non-coding micro RNAs (miRs), is strongly linked to free radical accumulation, cancer, and neurodegenerative diseases. The entry of micronutrients into the mitochondrial matrix depends upon the higher threshold level of mitochondrial membrane potential (ΔΨm), and high cytosolic micronutrients. The elevated micronutrient in the mitochondrial matrix causes the utilization of all ATP, leading to a drop in ATP levels. Mitochondrial calcium uniporter (MCU) and Na+/Ca2+ exchanger (NCX) play a major role in Ca2+ influx in the mitochondrial matrix. The mitochondrial Ca2+ overload is regulated by specific miRs such as miR1, miR7, miR25, miR145, miR138, and miR214, thereby reducing apoptosis and improving ATP production. Cuproptosis is primarily brought on by increased Cu+ build-up and mitochondrial proteotoxic stress, mediated by ferredoxin-1 (FDX1) and long non-coding RNAs. Cu importers (SLC31A1) and exporters (ATP7B) influence intracellular Cu2+ levels to control cuproptosis. According to literature reviews, very few randomized micronutrient interventions have been carried out, despite the identification of a high prevalence of micronutrient deficiencies. In this review, we concentrated on essential micronutrients and specific miRs associated with ATP production that balance oxidative stress in mitochondria.

Identification and experimental validation of ferroptosis-related gene SLC2A3 is involved in rheumatoid arthritis

BACKGROUND

Ferroptosis, an iron-dependent manner of lipid peroxidative cell death, has recently been reported to be strongly associated with rheumatoid arthritis (RA). Targeted ferroptosis may be a potential treatment for RA.

METHODS

We combined bioinformatics analysis and machine learning algorithm to screen the characteristic gene of RA. Moreover, we used gene set enrichment analysis (GSEA) to investigate the biological function of feature gene and CIBERSORT algorithm to analyze the correlation between selected hub gene and immune cells. The CellMiner database was used to predict potential drugs for RA. Finally, it was further verified by in vitro cell experiment.

RESULTS

SLC2A3 was identified as an important potential biomarker based on bioinformatics methods and machine learning algorithms. SLC2A3 encodes the predominantly neuronal glucose transporter 3 (GLUT3). GSEA showed that SLC2A3 high-expression group was correlated with metabolic pathways. Immune cell infiltration analysis showed that SLC2A3 was positively correlated with activated mast cell expression. RSL3 is an activator of ferroptosis that binds to and inactivates GPX4, mediating ferroptosis regulated by GPX4. In our experiment, we treated synovial fibroblast-like cells of RA (RA-FLS) with RSL3 (Ferroptosis inducers) and found that RSL3 can downregulate SLC2A3 expression and induce ferroptosis in RA-FLS.

CONCLUSIONS

Our study identifies and validates ferroptosis-related gene SLC2A3 as a potential biomarker for the diagnosis and treatment of RA. It was also found that RSL3 can induce ferroptosis in RA-FLS via lead to the downregulation of SLC2A3.

Fighting age-related orthopedic diseases: focusing on ferroptosis

Ferroptosis, a unique type of cell death, is characterized by iron-dependent accumulation and lipid peroxidation. It is closely related to multiple biological processes, including iron metabolism, polyunsaturated fatty acid metabolism, and the biosynthesis of compounds with antioxidant activities, including glutathione. In the past 10 years, increasing evidence has indicated a potentially strong relationship between ferroptosis and the onset and progression of age-related orthopedic diseases, such as osteoporosis and osteoarthritis. Therefore, in-depth knowledge of the regulatory mechanisms of ferroptosis in age-related orthopedic diseases may help improve disease treatment and prevention. This review provides an overview of recent research on ferroptosis and its influences on bone and cartilage homeostasis. It begins with a brief overview of systemic iron metabolism and ferroptosis, particularly the potential mechanisms of ferroptosis. It presents a discussion on the role of ferroptosis in age-related orthopedic diseases, including promotion of bone loss and cartilage degradation and the inhibition of osteogenesis. Finally, it focuses on the future of targeting ferroptosis to treat age-related orthopedic diseases with the intention of inspiring further clinical research and the development of therapeutic strategies.

Enriched Environment Attenuates Ferroptosis after Cerebral Ischemia/Reperfusion Injury via the HIF-1α-ACSL4 Pathway

Enriched environment (EE) has been proven to be an effective intervention strategy which can improve neurofunctional recovery following cerebral ischemia/reperfusion (I/R) injury. However, it still needs further investigation for the underlying mechanisms. Recently, it has been shown that ferroptosis played an essential role in the pathophysiological development of ischemic stroke (IS). This study is aimed at investigating whether EE plays a neuroprotective role by attenuating ferroptosis after cerebral I/R injury. We used middle cerebral artery occlusion/reperfusion (MCAO/R) to build a model of cerebral I/R injury. To evaluate the effect of EE on neurological recovery, we used the modified neurological severity score (mNSS) and the Morris water maze (MWM). We used the western blot to detect the protein levels of glutathione peroxidase 4 (GPX4), hypoxia-inducible factor-1α (HIF-1α), and acyl-CoA synthetase long-chain family member 4 (ACSL4). We used the quantitative real-time PCR (qRT-PCR) to measure the mRNA levels of ACSL4 and inflammatory cytokines including tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), and interleukin 1 beta (IL-1β). The occurrence of ferroptosis was detected by TdT-mediated dUTP nick-end labeling (TUNEL) assay, diaminobenzidine- (DAB-) enhanced Perls' staining, iron level assays, and malondialdehyde (MDA) level assays. The results verified that EE enhanced functional recovery and attenuated ferroptosis and neuroinflammation after cerebral I/R injury. EE increased the expression of HIF-1α while inhibited the expression of ACSL4. Our research indicated that EE improved functional recovery after cerebral I/R injury through attenuating ferroptosis, and this might be related to its regulation of the neuroinflammation and HIF-1α-ACSL4 pathway.

Cytokine Imbalance as a Biomarker of Intervertebral Disk Degeneration

The intervertebral disk degeneration (IDD) and its associated conditions are an important problem in modern medicine. The onset of IDD may be in childhood and adolescence in patients with a genetic predisposition. IDD progresses with age, leading to spondylosis, spondylarthrosis, intervertebral disk herniation, and spinal stenosis. The purpose of this review is an attempt to summarize the data characterizing the patterns of production of pro-inflammatory and anti-inflammatory cytokines in IDD and to appreciate the prognostic value of cytokine imbalance as its biomarker. This narrative review demonstrates that the problem of evaluating the contribution of pro-inflammatory and anti-inflammatory cytokines to the maintenance or alteration of cytokine balance may be a new key to unlocking the mystery of IDD development and new therapeutic strategies for the treatment of IDD in the setting of acute and chronic inflammation. The presented data support the hypothesis that cytokine imbalance is one of the most important biomarkers of IDD.

Emerging role of miRNAs in the regulation of ferroptosis

Ferroptosis is a kind of cell death which has distinctive features differentiating it from autophagy, necrosis and apoptosis. This iron-dependent form of cell death is described by an increase in lipid reactive oxygen species, shrinkage of mitochondria and decrease in mitochondrial cristae. Ferroptosis is involved in the initiation and progression of many diseases and is regarded as a hotspot of investigations on treatment of disorders. Recent studies have shown that microRNAs partake in the regulation of ferroptosis. The impact of microRNAs on this process has been verified in different cancers as well as intervertebral disc degeneration, acute myocardial infarction, vascular disease, intracerebral hemorrhage, preeclampsia, hemorrhagic stroke, atrial fibrillation, pulmonary fibrosis and atherosclerosis. miR-675, miR-93, miR-27a, miR-34a and miR-141 have been shown to affect iron metabolism, antioxidant metabolism and lipid metabolism, thus influencing all pivotal mechanisms in the ferroptosis process. In the current review, we summarize the role of microRNAs in ferroptosis and their involvement in the pathetiology of malignant and non-malignant disorders.

Molecular mechanisms of ferroptosis and relevance to inflammation

INTRODUCTION

Inflammation is a defensive response of the organism to irritation which is manifested by redness, swelling, heat, pain and dysfunction. The inflammatory response underlies the role of various diseases. Ferroptosis, a unique modality of cell death, driven by iron-dependent lipid peroxidation, is regulated by multifarious cellular metabolic pathways, including redox homeostasis, iron processing and metabolism of lipids, as well as various signaling pathways associated with diseases. A growing body of evidence suggests that ferroptosis is involved in inflammatory response, and targeting ferroptosis has great prospects in preventing and treating inflammatory diseases.

MATERIALS AND METHODS

Relevant literatures on ferroptosis, inflammation, inflammatory factors and inflammatory diseases published from January 1, 2010 to now were searched in PubMed database.

CONCLUSION

In this review, we summarize the regulatory mechanisms associated with ferroptosis, discuss the interaction between ferroptosis and inflammation, the role of mitochondria in inflammatory ferroptosis, and the role of targeting ferroptosis in inflammatory diseases. As more and more studies have confirmed the relationship between ferroptosis and inflammation in a wide range of organ damage and degeneration, drug induction and inhibition of ferroptosis has great potential in the treatment of immune and inflammatory diseases.

Targeting Ferroptosis Holds Potential for Intervertebral Disc Degeneration Therapy

Intervertebral disc degeneration (IVDD) is a common pathological condition responsible for lower back pain, which can significantly increase economic and social burdens. Although considerable efforts have been made to identify potential mechanisms of disc degeneration, the treatment of IVDD is not satisfactory. Ferroptosis, a recently reported form of regulated cell death (RCD), is characterized by iron-dependent lipid peroxidation and has been demonstrated to be responsible for a variety of degenerative diseases. Accumulating evidence suggests that ferroptosis is implicated in IVDD by decreasing viability and increasing extracellular matrix degradation of nucleus pulposus cells, annulus fibrosus cells, or endplate chondrocytes. In this review, we summarize the literature regarding ferroptosis of intervertebral disc cells and discuss its molecular pathways and biomarkers for treating IVDD. Importantly, ferroptosis is verified as a promising therapeutic target for IVDD.

Is intervertebral disc degeneration associated with reduction in serum ferritin?

OBJECTIVE

Ferritin autophagy is characterized by intracellular ferroptosis and selective ferritin degradation. However, the role of ferritin in the development of intervertebral disc degeneration (IDD) has not been elucidated. The study aimed to investigate the role of serum iron metabolism markers, especially serum ferritin (SF), in IDD.

METHODS

217 patients who came to the spine surgery department of our hospital for low back pain were recruited, and blood samples were collected for routine examination after admission. The cumulative grade was also calculated by summing up the Pfirrmann grade of all lumbar discs.

RESULTS

Correlation analysis showed that cumulative grade was correlated with SF (r = - 0.185, p = 0.006), not with serum iron (SI), transferrin saturation (TS), unsaturated iron-binding capacity (UIBC) and total iron-binding capacity (TIBC) (all p > 0.05). In addition, SF levels in the low severity IDD were significantly higher than high severity IDD in cumulative grade (p = 0.003) and single disc grade. No statistically significant difference was found in the other four indicators. A statistically significant difference was observed between the high (cumulative grade > 17) and low score (cumulative grade ≤ 17) groups in terms of age. According to the ROC curve, the cut-off value of SF levels was 170.5. Patients with SF < 170.5 ng/mL had severe disc degeneration. The sensitivity and specificity were 0.635 and 0.602, respectively.

CONCLUSION

This study preliminarily showed that SF was negatively correlated with the degree of IDD and can be used to predict IDD severity.

Pyroptosis and Intervertebral Disc Degeneration: Mechanistic Insights and Therapeutic Implications

Low back pain (LBP) is a common problem worldwide, resulting in great patient suffering and great challenges for the social health system. Intervertebral disc (IVD) degeneration (IVDD) is widely acknowledged as one of the key causes of LBP. Accumulating evidence suggests that aberrant pyroptosis of IVD cells is involved in the pathogenesis of IVDD progression, however, the comprehensive roles of pyroptosis in IVDD have not been fully established, leaving attempts to treat IVDD with anti-pyroptosis approaches questionable. In this review, we summarize the characteristics of pyroptosis and emphasize the effects of IVD cell pyroptosis on the pathological progression of IVDD, including secretion of cytokines, nucleus pulposus cell apoptosis and autophagy, accelerated extracellular matrix degradation, annulus fibrosus rupture, cartilage endplate calcification, vascularization, sensory and sympathetic fiber neoinnervation, and infiltrating lymphatic vessels. Finally, we discuss several interventions used to treat IVDD by targeting pyroptosis. This review provides novel insights into the crucial role of IVD cell pyroptosis in IVDD pathogenesis, and could be informative for developing novel therapeutic approaches for IVDD and LBP.

Ferroptosis and musculoskeletal diseases: “Iron Maiden” cell death may be a promising therapeutic target

Ferroptosis is a novel form of cell death precisely regulated by iron metabolism, antioxidant processes, and lipid metabolism that plays an irreplaceable role in the development of many diseases. Musculoskeletal disorders (MSKs), including osteoporosis, osteoarthritis, rheumatoid arthritis, intervertebral disc degeneration, sarcopenia, and rhabdomyolysis, have become one of the most common causes of disability and a major burden on public health and social care systems. The mechanism of ferroptosis in MSKs has recently been elucidated. In this review, we briefly introduce the ferroptosis mechanism and illustrate the pathological roles of ferroptosis in MSKs with a focus on how ferroptosis can be exploited as a promising treatment strategy. Notably, because the toxicity of compounds that inhibit or induce ferroptosis in other organs is largely unknown, ferroptosis appears to be a double-edged sword. We point out that more research is needed in the future to verify the therapeutic effects based on ferroptosis in MSKs.

Identification of differentially expressed ferroptosis-related genes in abdominal aortic aneurysm: Bioinformatics analysis

Purpose

Ferroptosis plays a crucial role in the development and progression of abdominal aortic aneurysm (AAA). The aim of this study was to identify differentially expressed genes associated with ferroptosis in AAA through bioinformatics analysis combined with experimental validation.

Materials and methods

Firstly, the mRNA expression profile datasets GSE57691 and GSE47472 from Gene Expression Omnibus database were screened, and principal component analysis was carried out. Next, the R software (version 4.0.0) was used to analyze potentially differentially expressed genes associated with AAA and ferroptosis. Subsequently, protein–protein interaction analysis, gene ontology enrichment analysis, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were performed on the selected candidate genes. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of the first five selected abnormal ferroptosis-related genes in clinical samples obtained from patients with AAA and healthy controls.

Results

Based on the information contained in the two datasets, a total of 20 differentially expressed ferroptosis-related genes (three upregulated genes and 17 downregulated genes) were selected. Protein–protein interaction analysis demonstrated interaction between these genes, while gene ontology enrichment analysis of ferroptosis genes with differential expression indicated that some enrichment items were associated with oxidative stress. The qRT-PCR results showed that the expression levels of interleukin-6 (IL-6), peroxiredoxin 1 (PRDX1), and stearoyl-CoA desaturase (SCD) were consistent with the bioinformatics prediction results obtained from the mRNA chip.

Conclusion

Bioinformatics analysis identified 20 potential ferroptosis-related differentially expressed genes in AAA. Further verification by qRT-PCR showed that IL-6, PRXD1, and SCD might affect the process of AAA by regulating ferroptosis. Our results might assist in further understanding the pathogenesis of AAA and guiding treatment.

Micro-Players of Great Significance-Host microRNA Signature in Viral Infections in Humans and Animals

Over time, more and more is becoming known about micro-players of great significance. This is particularly the case for microRNAs (miRNAs; miR), which have been found to participate in the regulation of many physiological and pathological processes in both humans and animals. One such process is viral infection in humans and animals, in which the host miRNAs—alone or in conjunction with the virus—interact on two levels: viruses may regulate the host’s miRNAs to evade its immune system, while the host miRNAs can play anti- or pro-viral roles. The purpose of this comprehensive review is to present the key miRNAs involved in viral infections in humans and animals. We summarize the data in the available literature, indicating that the signature miRNAs in human viral infections mainly include 12 miRNAs (i.e., miR-155, miR-223, miR-146a, miR-122, miR-125b, miR-132, miR-34a, miR -21, miR-16, miR-181 family, let-7 family, and miR-10a), while 10 miRNAs are commonly found in animals (i.e., miR-155, miR-223, miR-146a, miR-145, miR-21, miR-15a/miR-16 cluster, miR-181 family, let-7 family, and miR-122) in this context. Knowledge of which miRNAs are involved in different viral infections and the biological functions that they play can help in understanding the pathogenesis of viral diseases, facilitating the future development of therapeutic agents for both humans and animals.

Analysis of the potential ferroptosis mechanism and multitemporal expression change of central ferroptosis-related genes in cardiac ischemia–reperfusion injury

Acute myocardial infraction is the most severe type of coronary artery disease and remains a substantial burden to the health care system globally. Although myocardial reperfusion is critical for ischemic cardiac tissue survival, the reperfusion itself could cause paradoxical injury. This paradoxical phenomenon is known as ischemia–reperfusion injury (IRI), and the exact molecular mechanism of IRI is still far from being elucidated and is a topic of controversy. Meanwhile, ferroptosis is a nonapoptotic form of cell death that has been reported to be associated with various cardiovascular diseases. Thus, we explored the potential ferroptosis mechanism and target in cardiac IRI via bioinformatics analysis and experiment. GSE4105 data were obtained from the GEO database and consist of a rat IRI model and control. After identifying differentially expressed ferroptosis-related genes (DEFRGs) and hub genes of cardiac IRI, we performed enrichment analysis, coexpression analysis, drug–gene interaction prediction, and mRNA–miRNA regulatory network construction. Moreover, we validated and explored the multitemporal expression of hub genes in a hypoxia/reoxygenation (H/R)-induced H9C2 cell injury model under different conditions via RT-qPCR. A total of 43 DEFRGs and 7 hub genes (tumor protein p53 [Tp53], tumor necrosis factor [Tnf], hypoxia-inducible factor 1 subunit alpha [Hif1a], interleukin 6 [Il6], heme oxygenase 1 [Hmox1], X-box binding protein 1 [Xbp1], and caspase 8 [Casp8]) were screened based on bioinformatics analysis. The functional annotation of these genes revealed apoptosis, and the related signaling pathways could have association with the pathogenesis of ferroptosis in cardiac IRI. In addition, the expression of the seven hub genes in IRI models were found higher than that of control under different H/R conditions and time points. In conclusion, the analysis of 43 DEFRGs and 7 hub genes could reveal the potential biological pathway and mechanism of ferroptosis in cardiac IRI. In addition, the multitemporal expression change of hub genes in H9C2 cells under different H/R conditions could provide clues for further ferroptosis mechanism exploring, and the seven hub genes could be potential biomarkers or therapeutic targets in cardiac IRI.

Emerging Potential Therapeutic Targets of Ferroptosis in Skeletal Diseases

Ferroptosis is a new programmed cell death characterized by the accumulation of lipid peroxidation mediated by iron and inflammation. Since the transcentury realization of ferroptosis as an iron-dependent modality of nonapoptotic cell death in 2012, there has been growing interest in the function of ferroptosis and its relationship to clinical diseases. Recent studies have shown that ferroptosis is associated with multiple diseases, including degenerative diseases, ischemia reperfusion injury, cardiovascular disease, and cancer. Cell death induced by ferroptosis has also been related to several skeletal diseases, such as inflammatory arthritis, osteoporosis, and osteoarthritis. Research on ferroptosis can clarify the pathogenesis of skeletal diseases and provide a novel therapeutic target for its treatment. In this review, we summarize current information about the molecular mechanism of ferroptosis and describe its emerging role and therapeutic potential in skeletal diseases.

Identification of Core Genes and Screening of Potential Targets in Intervertebral Disc Degeneration Using Integrated Bioinformatics Analysis

Background: Intervertebral disc degeneration (IDD), characterized by diverse pathological changes, causes low back pain (LBP). However, prophylactic and delaying treatments for IDD are limited. The aim of our study was to investigate the gene network and biomarkers of IDD and suggest potential therapeutic targets.

Methods: Differentially expressed genes (DEGs) associated with IDD were identified by analyzing the mRNA, miRNA, and lncRNA expression profiles of IDD cases from the Gene Expression Omnibus (GEO). The protein–protein interaction (PPI) network, Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis as well as miRNA–lncRNA–mRNA networks were conducted. Moreover, we obtained 71 hub genes and performed a comprehensive analysis including GO, KEGG, gene set enrichment analysis (GSEA), gene set variation analysis (GSVA), Disease Ontology (DO), methylation analysis, receiver operating characteristic (ROC) curve analysis, immune infiltration analysis, and potential drug identification. We finally used qRT-PCR to verify 13 significant DEGs in normal and degenerative nucleus pulposus cells (NPCs).

Results: We identified 305 DEGs closely related to IDD. The GO and KEGG analyses indicated that changes in IDD are significantly associated with enrichment of the inflammatory and immune response. GSEA analysis suggested that cell activation involved in the inflammatory immune response amide biosynthetic process was the key for the development of IDD. The GSVA suggested that DNA repair, oxidative phosphorylation, peroxisome, IL-6-JAK-STAT3 signaling, and apoptosis were crucial in the development of IDD. Among the 71 hub genes, the methylation levels of 11 genes were increased in IDD. A total of twenty genes showed a high functional similarity and diagnostic value in IDD. The result of the immune cell infiltration analysis indicated that seven genes were closely related to active natural killer cells. The most relevant targeted hub genes for potential drug or molecular compounds were MET and PIK3CD. Also, qRT-PCR results showed that ARHGAP27, C15orf39, DEPDC1, DHRSX, MGAM, SLC11A1, SMC4, and LINC00887 were significantly downregulated in degenerative NPCs; H19, LINC00685, mir-185-5p, and mir-4306 were upregulated in degenerative NPCs; and the expression level of mir-663a did not change significantly in normal and degenerative NPCs.

Conclusion: Our findings may provide new insights into the functional characteristics and mechanism of IDD and aid the development of IDD therapeutics.

Downregulation of the CsABCC2 gene is associated with Cry1C resistance in the striped stem borer Chilo suppressalis

Chilo suppressalis is a major target pest of transgenic rice expressing the Bacillus thuringiensis (Bt) Cry1C toxin in China. The evolution of resistance of this pest is a major threat to Bt rice. Since Bt functions by binding to receptors in the midgut (MG) of target insects, identification of Bt functional receptors in C. suppressalis is crucial for evaluating potential resistance mechanisms and developing effective management strategies. ATP-binding cassette (ABC) transporters have been vastly reported to interact with Cry1A toxins, as receptors and their mutations cause insect Bt resistance. However, the role of ABC transporters in Cry1C resistance to C. suppressalis remains unknown. Here, we measured CsABCC2 expression in C. suppressalis Cry1C-resistant (Cry1C-R) and Cry1C-susceptible strains (selected in the laboratory) via quantitative real-time PCR (qRT-PCR); the transcript level of CsABCC2 in the Cry1C-R strain was significantly lower than that in the Cry1C-susceptible strain. Furthermore, silencing CsABCC2 in C. suppressalis via RNA interference (RNAi) significantly decreased Cry1C susceptibility. Overall, CsABCC2 participates in Cry1C mode of action, and reduced expression of CsABCC2 is functionally associated with Cry1C resistance in C. suppressalis.

Immunomodulatory Properties of Human Breast Milk: MicroRNA Contents and Potential Epigenetic Effects

Infants who are exclusively breastfed in the first six months of age receive adequate nutrients, achieving optimal immune protection and growth. In addition to the known nutritional components of human breast milk (HBM), i.e., water, carbohydrates, fats and proteins, it is also a rich source of microRNAs, which impact epigenetic mechanisms. This comprehensive work presents an up-to-date overview of the immunomodulatory constituents of HBM, highlighting its content of circulating microRNAs. The epigenetic effects of HBM are discussed, especially those regulated by miRNAs. HBM contains more than 1400 microRNAs. The majority of these microRNAs originate from the lactating gland and are based on the remodeling of cells in the gland during breastfeeding. These miRNAs can affect epigenetic patterns by several mechanisms, including DNA methylation, histone modifications and RNA regulation, which could ultimately result in alterations in gene expressions. Therefore, the unique microRNA profile of HBM, including exosomal microRNAs, is implicated in the regulation of the genes responsible for a variety of immunological and physiological functions, such as FTO, INS, IGF1, NRF2, GLUT1 and FOXP3 genes. Hence, studying the HBM miRNA composition is important for improving the nutritional approaches for pregnancy and infant's early life and preventing diseases that could occur in the future. Interestingly, the composition of miRNAs in HBM is affected by multiple factors, including diet, environmental and genetic factors.

Potential role of selenium in alleviating obesity-related iron dyshomeostasis

Obesity is a serious health problem in modern life and increases the risk of many comorbidities including iron dyshomeostasis. In contrast to malnourished anemia, obesity-related iron dyshomeostasis is mainly caused by excessive fat accumulation, inflammation, and disordered gut microbiota. In obesity, iron dyshomeostasis also induces disorders associated with gut microbiota, neurodegenerative injury, oxidative damage, and fat accumulation in the liver. Selenium deficiency is often accompanied by obesity or iron deficiency, and selenium supplementation has been shown to alleviate obesity and overcome iron deficiency. Selenium inhibits fat accumulation and exhibits anti-inflammatory activity. It regulates gut microbiota, prevents neurodegenerative injury, alleviates oxidative damage to the body, and ameliorates hepatic fat accumulation. These effects theoretically meet the requirements for the inhibition of factors underlying obesity-related iron dyshomeostasis. Selenium supplementation may have a potential role in the alleviation of obesity-related iron dyshomeostasis. This review verifies this hypothesis in theory. All the currently reported causes and results of obesity-related iron dyshomeostasis are reviewed comprehensively, together with the effects of selenium. The challenges and strategies of selenium supplementation are also discussed. The findings demonstrate the possibility of selenium-containing drugs or functional foods in alleviating obesity-related iron dyshomeostasis.

Inhibition of USP14 suppresses ferroptosis and inflammation in LPS-induced goat mammary epithelial cells through ubiquitylating the IL-6 protein

Background

Ferroptosis, a novel manner of cell death depended on iron ion, contributed to goat mammary epithelial cell dysfunction. Interleukin-6 (IL-6) is a major pro-inflammatory factor during many inflammation-related diseases including mastitis, and a quite recently identified ferroptosis inducer. This study aims to explore the role of IL-6 in the dysfunction of goat mammary epithelial cells (GMECs) and how the level of IL-6 was regulated.

Methods

Primary GMECs were isolated, cultured and treated with lipopolysaccharide (LPS) alone or together with Ferrostatin-1 (Fer-1), a well-known ferroptosis inhibitor. CCK-8 was used to detect cell viability, ELISA was used to detect TNF-α content, and the levels of ROS, GSH and MDA were analyzed with DCFDA-cell ROS detection kit, GSH assay kit and MDA assay kit, respectively. The iron ion level was measured with an iron assay kit.

Results

The expression level of IL-6 protein in GMECs was up-regulated in response to LPS treatment, and the secretion of TNF-α, the cell oxidative stress level and the Fe²⁺ ion content was robustly increased, which could be reversed by Fer-1 treatment. Knockdown of IL-6 decreased cell oxidative stress level and inhibited ferroptosis in LPS-treated GMECs. Further, ubiquitin experiment and co-immunoprecipitation assay showed that USP14 upregulated IL-6 protein expression by reducing the ubiquitination of IL-6, and overexpression of IL-6 reversed the inhibitory effect of USP14 shRNA on LPS-treated GMECs ferroptosis. The NRF2 inhibitor Brusatol reversed the inhibitory effect of IL-6 shRNA on LPS-treated ferroptosis.

Conclusion

IL-6 protein is deubiquitinated by USP14 and upregulated in LPS-treated GMECs, further promoting ferroptosis and inflammation through the NRF2 signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41065-022-00235-y.

PRDX2 Knockdown Inhibits Extracellular Matrix Synthesis of Chondrocytes by Inhibiting Wnt5a/YAP1/CTGF and Activating IL-6/JAK2/STAT3 Pathways in Deer Antler

Although peroxiredoxin 2 (PRDX2) plays a vital role in relieving oxidative stress, its physiological function in cartilage development remains almost unknown. In this study, we found that the expression of PRDX2 significantly increased in the chondrocytes compared with pre-chondrocytes. PRDX2 knockdown significantly decreased the expression of extracellular matrix (ECM) protein (Col2a and Aggrecan), which led to blocked cartilage formation. Moreover, PRDX2 knockdown also inhibited the expression of connective tissue growth factor (CTGF). CTGF is an important growth factor that regulates synthesis of ECM proteins. We explored the possible regulatory mechanism by which PRDX2 regulated the expression of CTGF. Our results demonstrated that PRDX2 knockdown downregulated the expression of CTGF by inhibiting Wnt5a/Yes-associated protein 1 (YAP1) pathway. In addition, PRDX2 knockdown promoted the expression of interleukin 6 (IL-6), indicating PRDX2 expression had an anti-inflammatory function during antler growth. Mechanistically, PRDX2 knockdown promoted cartilage matrix degradation by activating the IL-6-mediated Janus Kinase 2/Signal Transducer and Activator of Transcription 3 (JAK2/STAT3) signaling pathway. These results reveal that PRDX2 is a potential regulator that promotes cartilage extracellular matrix synthesis.

Ferroptosis is involved in PGPS-induced otitis media in C57BL/6 mice

Otitis media (OM) is a common disease that can cause hearing loss in children. Currently, the main clinical treatment for OM is antibiotics, but the overuse of antibiotics might lead to bacterial resistance, which is a worldwide public health challenge. Studying the pathogenesis of OM will help us develop new effective treatments. Ferroptosis is one type of programmed cell death characterized by the occurrence of lipid peroxidation driven by iron ions. Many studies have shown that ferroptosis is associated with infectious diseases. It is presently unclear whether ferroptosis is involved in the pathogenesis of OM. In this study, we explored the relationship between ferroptosis and OM by PGPS-induced OM in C57BL/6 mice and treating the induced OM with ferroptosis inhibitors deferoxamine (DFO), Ferrostatin-1 (Fer-1), and Liperoxstatin-1 (Lip-1). We examined the expression of ferroptosis-related proteins acyl-CoA synthetase long chain family member 4 (ACSL4) and prostaglandin-endoperoxide synthase 2 (Cox2), glutathione peroxidase 4 (GPX4) protein as well as lipid peroxidation markers 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA). The results showed that in PGPS-induced OM model mice, several ferroptosis-related proteins including ACSL4 and Cox2 were up-regulated compared to mice treated with saline. Meanwhile, a ferroptosis-related protein GPX4 was down-regulated upon PGPS treatment. The DFO treatment in PGPS-inoculated mice effectively inhibited the development of OM. The inhibitors treatment caused a significant decrease in the expression of ACSL4, Cox2, 4 HNE, MDA, reduction in free iron. Meanwhile, the ferroptosis inhibitors treatment caused increase in the expression of inflammation-related factors tumor necrosis factor-α (TNF-α) and antioxidant protein GPX4. Our results suggest that there is a crosstalk between ferroptosis signaling pathway and the pathogenesis of OM. Ferroptosis inhibition can alleviate PGPS-induced OM.

Integrated Analysis of Ferroptosis and Immunity-Related Genes Associated with Intestinal Ischemia/Reperfusion Injury

Purpose

Intestinal ischemia/reperfusion (I/R) injury is an unresolved clinical challenge due to its high prevalence, difficulty in diagnosis, and lack of clinically effective therapeutic agents. Ferroptosis is a novel form of cell-regulated death that has been shown to play a role in various I/R models and has been shown to be immune-related. Further unraveling the molecular mechanisms associated with ferroptosis and immunity in intestinal I/R injury may lead to the discovery of potentially effective drugs.

Methods

We obtained differentially expressed mRNAs (DEGs) in mouse intestinal tissues following intestinal I/R injury or sham surgery. Then, we extracted ferroptosis-related DEGs (FRGs) and immune-related DEGs (IRGs) from the DEGs. In addition, we performed functional analysis of FRGs and IRGs. Next, we used transcriptome sequencing from patients with intestinal I/R injury to validate the results. Then, we constructed transcription factors (TFs)-gene networks and gene-drug networks using mouse and human co-expressed FRGs (coFRG) and mouse and human co-expressed IRGs (coIRG). We also analyzed the composition of immune cells to reveal correlations between FRGs signatures and immune cells in the mouse and human gut. Finally, we validated these results through animal experiments.

Results

We extracted 61 FRGs and 294 IRGs from mouse samples and performed PPI and functional analyses. We extracted 45 FRGs and 200 IRGs from human samples for validation, and identified 24 coFRGs,100 coIRGs and 6 hub genes (HSPA5, GDF15, TNFAIP3, HMOX1, CXCL2 and IL6) in both. We also predicted potential TF-gene networks for coFRGs and coIRGs, as well as predicted gene-drug pairs for hub genes. In addition, we found that the immune cells were altered in the early stages of intestinal I/R injury and that FRGs were closely associated with immune cells in mice and humans. Finally, we validated the hub genes in mouse samples.

Conclusion

In conclusion, we identified ferroptosis and immunity-related genes to predict their correlations in intestinal I/R injury. We also predicated potential TF-genes network and potential therapeutic targets (HSPA5, GDF15, TNFAIP3, HMOX1, CXCL2 and IL6) to provide clues for further investigation of intestinal I/R injury.

The role of non-coding RNAs in ferroptosis regulation

Ferroptosis is a newly recognized form of cell death that is distinct from apoptosis, necrosis, autophagy in morphology, biochemistry, and heredity. The basic process of ferroptosis involves disordered permeability of plasma membrane, which is caused by abnormal accumulation of lipids and reactive oxygen species (ROS). The regulatory mechanism of ferroptosis is important due to its involvement in tumor progression, neurotoxicity, neurodegenerative diseases, acute renal failure, and ischemia-reperfusion injury. Recent studies have shown that in ferroptosis metabolism, non-coding RNAs (ncRNAs) can interfere with multiple signaling pathways at both the pre-transcriptional and post-transcriptional levels. Despite great progress, current research on the mechanism of ncRNAs and ferroptosis remains insufficient. This review provides an overview of the main mechanisms and targets of ferroptosis and focuses on the mechanisms of non-coding RNA regulation. Analyzing the deficiencies in current research may provide ideas for future studies to investigate.

Construction of a Ferroptosis-Related Gene Signature for Head and Neck Squamous Cell Carcinoma Prognosis Prediction

Background

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignant cancers, and few studies have demonstrated the value of ferroptosis-related genes in prognosis.

Methods

The original counts of RNA sequencing data and clinicopathological data were obtained from TCGA and GSE65858 datasets. Common ferroptosis-related genes related to prognosis were identified from the training set and were included in LASSO to determine the best prognosis. To evaluate the efficacy, time-dependent ROC and Kaplan–Meier (KM) survival analyses were applied. Moreover, univariate and multivariate Cox regression analyses were used to screen independent parameters of prognosis and build a nomogram. Eventually, possible biological pathways were proposed based on GSEA.

Results

Among 242 ferroptosis-related genes, we identified that the FLT3, IL6, Keap1, NQO1, SOCS1 and TRIB3 genes were significantly connected with HNSCC patient prognosis as a six-gene signature. After, the patients were divided into high- and low-risk groups based on the six-gene signature. The KM survival curves demonstrated that the high-risk group had worse OS (p < 0.0001) and higher AUC values (0.654, 0.735, and 0.679 for 1-, 3-, and 5-year survival, respectively) for the prognostic signature of the six genes compared with other genes, which were also validated in the GSE65858 dataset. Moreover, GSEA suggested that the epithelial mesenchymal transition pathway was abundant and that the mesenchymal status in the high-risk group was substantially higher than that in the low-risk group. Finally, the immune microenvironment and differences in the content of immune cell types were demonstrated.

Conclusion

We established a six-ferroptosis-related-gene model crossing clinical prognostic parameters that can predict HNSCC patient prognosis and provide a reliable prognostic evaluation tool to assist clinical treatment decisions.

The potential mechanisms and application prospects of non-coding RNAs in intervertebral disc degeneration

Low back pain (LBP) is one of the most common musculoskeletal symptoms and severely affects patient quality of life. The majority of people may suffer from LBP during their life-span, which leading to huge economic burdens to family and society. According to the series of the previous studies, intervertebral disc degeneration (IDD) is considered as the major contributor resulting in LBP. Furthermore, non-coding RNAs (ncRNAs), mainly including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), can regulate diverse cellular processes, which have been found to play pivotal roles in the development of IDD. However, the potential mechanisms of action for ncRNAs in the processes of IDD are still completely unrevealed. Therefore, it is challenging to consider ncRNAs to be used as the potential therapeutic targets for IDD. In this paper, we reviewed the current research progress and findings on ncRNAs in IDD: i). ncRNAs mainly participate in the process of IDD through regulating apoptosis of nucleus pulposus (NP) cells, metabolism of extracellular matrix (ECM) and inflammatory response; ii). the roles of miRNAs/lncRNAs/circRNAs are cross-talk in IDD development, which is similar to the network and can modulate each other; iii). ncRNAs have been attempted to combat the degenerative processes and may be promising as an efficient bio-therapeutic strategy in the future. Hence, this review systematically summarizes the principal pathomechanisms of IDD and shed light on the therapeutic potentials of ncRNAs in IDD.

Ferroptosis: A potential target for the intervention of intervertebral disc degeneration

Ferroptosis, an iron-dependent form of programmed cell death marked by phospholipid peroxidation, is regulated by complex cellular metabolic pathways including lipid metabolism, iron balance, redox homeostasis, and mitochondrial activity. Initial research regarding the mechanism of ferroptosis mainly focused on the solute carrier family 7 member 11/glutathione/glutathione peroxidase 4 (GPX4) signal pathway. Recently, novel mechanisms of ferroptosis, independent of GPX4, have been discovered. Numerous pathologies associated with extensive lipid peroxidation, such as drug-resistant cancers, ischemic organ injuries, and neurodegenerative diseases, are driven by ferroptosis. Ferroptosis is a new therapeutic target for the intervention of IVDD. The role of ferroptosis in the modulation of intervertebral disc degeneration (IVDD) is a significant topic of interest. This is a novel research topic, and research on the mechanisms of IVDD and ferroptosis is ongoing. Herein, we aim to review and discuss the literature to explore the mechanisms of ferroptosis, the relationship between IVDD and ferroptosis, and the regulatory networks in the cells of the nucleus pulposus, annulus fibrosus, and cartilage endplate to provide references for future basic research and clinical translation for IVDD treatment.

Interleukin-6 promotes ferroptosis in bronchial epithelial cells by inducing reactive oxygen species-dependent lipid peroxidation and disrupting iron homeostasis

Asthma occurs accompanied by the ferroptosis in bronchial epithelial cells, during which Interleukin-6 (IL-6) plays a key role. However, the associations between IL-6, ferroptosis and asthma have not been reported. Bronchial epithelial cells BEAS-2B cells were induced by different concentrations of IL-6 and cell viability was detected by MTT assay. The TBARS production rate was detected by corresponding kit. The expression of oxidative stress-related indexes was detected by ELISA. The Iron Assay Kits detected total iron levels and ferrous ion (Fe²⁺) levels. Labile iron pool assay was used to detect the cell unstable iron pool. The expression of ferroptosis-related proteins was detected by Western blot. To further examine the mechanism of action, ferroptosis inhibitor Ferrostatin 1 (Fer-1), antioxidant NAC, and the iron supplement Fe were added. We found that IL-6 decreased the activity, promoted lipid peroxidation, disrupted iron homeostasis of BEAS-2B cells, and induced iron death in bronchial epithelial BEAS-2B cells. However, pretreatment with Ferrostatin-1 (Fer-1) and antioxidant NAC partially reversed the effect of IL-6 on lipid peroxidation and ferroptosis in BEAS-2B cells, while Fe augmented the effect. Overall, IL-6 promotes ferroptosis in bronchial epithelial cells by inducing reactive oxygen species (ROS)-dependent lipid peroxidation and disrupting iron homeostasis.